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FXUS06 KWBC 171925
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE OCTOBER 17 2017

6-10 DAY OUTLOOK FOR OCT 23 - 27 2017

TODAY`S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT ON AN AMPLIFIED FLOW
PATTERN OVER MOST OF THE FORECAST DOMAIN. A DEEP, CLOSED 500-HPA TROUGH IS
FORECAST OVER PARTS OF WESTERN ALASKA, WITH NEGATIVE HEIGHT ANOMALIES EXTENDING
SOUTHWARD TO NEAR HAWAII. DOWNSTREAM A STRONG RIDGE IS PREDICTED OVER THE
WESTERN HALF OF THE CONUS. A TROUGH IS FORECAST OVER THE EASTERN HALF OF THE
CONUS. TODAY`S 500-HPA MANUAL BLEND FEATURES NEGATIVE HEIGHT ANOMALIES OVER ALL
OF ALASKA, POSITIVE HEIGHT ANOMALIES OVER THE WESTERN HALF OF THE CONUS, AND
NEGATIVE HEIGHT ANOMALIES OVER THE EASTERN HALF OF THE CONUS.

BELOW NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF WESTERN ALASKA DUE TO A DEEP
TROUGH PREDICTED OVER PARTS OF WESTERN ALASKA. A STRONG RIDGE PREDICTED OVER
THE WESTERN CONUS HIGHLY FAVORS ABOVE NORMAL TEMPERATURES FOR THE WESTERN HALF
OF THE CONUS, ESPECIALLY FOR SOUTHERN CALIFORNIA AND PARTS OF THE SOUTHWEST,
WHERE THE PREDICTED RIDGE IS CENTERED. A FORECAST DEEPENING TROUGH AND A
FRONTAL PASSAGE INCREASE THE LIKELIHOOD OF BELOW NORMAL TEMPERATURES FOR PARTS
OF THE SOUTHERN PLAINS, THE SOUTHERN AND CENTRAL MISSISSIPPI VALLEYS, AND THE
SOUTHEAST. THIS IS IN CONTRAST TO YESTERDAY`S OFFICIAL 6-10 DAY OUTLOOK WHICH
FAVORED ABOVE NORMAL TEMPERATURES IN THE SOUTHEAST, AS TODAY`S MODELS HAVE
SIGNIFICANTLY INCREASED THE STRENGTH OF THE TROUGH FORECAST IN THE EASTERN U.S.
IN PARTS OF THE MID-ATLANTIC AND NORTHEAST, LARGE POSITIVE TEMPERATURE
ANOMALIES FORECAST IN THE BEGINNING OF THE PERIOD FAVOR ABOVE NORMAL
TEMPERATURES IN THOSE REGIONS.

STORM SYSTEM ACTIVITY IS FORECAST TO TRAVEL AROUND THE CLOSED LOW OVER PARTS OF
ALASKA, INCREASING THE LIKELIHOOD FOR ABOVE NORMAL PRECIPITATION FOR THE
ALEUTIANS, THE SOUTHERN ALASKA COAST, THE ALASKA PANHANDLE, AND EXTREME
NORTHERN PORTIONS OF THE PACIFIC NORTHWEST. THE WESTERN RIDGE IS FORECAST TO
STORM SYSTEMS FROM COMING INTO THE WESTERN CONUS, STRONGLY FAVORING BELOW
NORMAL PRECIPITATION OVER MUCH OF THE WESTERN HALF OF THE CONUS. THOUGH
YESTERDAY`S OFFICIAL 6-10 DAY OUTLOOK FEATURED ABOVE NORMAL PRECIPITATION FOR
PARTS OF THE SOUTHERN PLAINS, THE PREDICTED FRONT RESPONSIBLE FOR THIS IS
FORECAST TO BE EAST OF THE MISSISSIPPI BY TODAY`S MODELS, FAVORING ABOVE NORMAL
PRECIPITATION EAST OF THE MISSISSIPPI.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 50% OF TODAY`S 6Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, AND 50% OF TODAY`S OPERATIONAL 12Z GFS CENTERED ON DAY 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG THE MODELS, OFFSET BY SOME LARGE-SCALE DIFFERENCES AMONG THE
TEMPERATURE AND PRECIPITATION TOOLS.

8-14 DAY OUTLOOK FOR OCT 25 - 31 2017

DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW PATTERN IS EXPECTED TO
RETROGRADE SLIGHTLY, AND BE SLIGHTLY LESS AMPLIFIED, WHICH IS EXPECTED GIVEN
THE INCREASED ENSEMBLE SPREAD REDUCING THE AMPLITUDE OF THE ENSEMBLE MEANS.

THE TEMPERATURE PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE VERY
SIMILAR TO THOSE FORECAST DURING THE WEEK-2 PERIOD, WITH A COUPLE OF
EXCEPTIONS. SOME RIDGING IS EXPECTED TO BUILD WESTWARD INTO EASTERN PORTIONS OF
ALASKA, FAVORING ABOVE NORMAL TEMPERATURES THERE. AS THE EASTERN TROUGH IS
FORECAST TO BECOME MORE ESTABLISHED DURING THE WEEK-2 PERIOD, THE FAVORED AREA
OF BELOW NORMAL TEMPERATURES IS LARGER DURING THE WEEK-2 PERIOD.

THE PRECIPITATION PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR
TO THE WEEK-2 PERIOD, EXCEPT THAT THE FRONTAL SYSTEM FORECAST TO FAVOR ABOVE
NORMAL PRECIPITATION IN THE EASTERN U.S. DURING THE 6-10 DAY PERIOD IS
PREDICTED TO MOVE OFFSHORE DURING THE BEGINNING OF THE WEEK-2 PERIOD, LEAVING
ONLY THE NORTHEAST IN THE REGION OF FAVORED ABOVE NORMAL PRECIPITATION.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 60% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, AND 40% OF TODAY`S OPERATIONAL 0Z GFS CENTERED ON DAY
11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE MODELS, OFFSET BY SOME LARGE-SCALE DIFFERENCES AMONG
THE TEMPERATURE AND PRECIPITATION TOOLS.

FORECASTER: MIKE C

NOTES:


AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES.
IN THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT
ISSUED.

THE NOTATION FOR THE CATEGORICAL FORECAST INDICATED ON THE MAPS IS
THE SAME AS THAT IN THE TABLES: A-ABOVE   N-NEAR NORMAL   B-BELOW

THE TEMPERATURE MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WARMER
(ORANGE, "A"), COLDER (BLUE, "B"), OR CLOSE TO (UNSHADED, "N")
HISTORICAL AVERAGE VALUES FOR THE CALENDAR PERIOD OF THE FORECAST
(DASHES, "F").  LABELS ON THE SHADED LINES GIVE THE PROBABILITY
(> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  PROBABILITY OF N IS
ALWAYS < 40%.

THE PRECIPITATION MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING
WETTER (GREEN, "A"), DRIER (TAN, "B"), OR CLOSE TO (UNSHADED, "N")
HISTORICAL MEDIAN VALUES FOR THE CALENDAR PERIOD OF THE FORECAST
(DASHES, "INCHES").  LABELS ON THE SHADED LINES GIVE THE PROBABILITY
(> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  PROBABILITY OF N IS
ALWAYS < 40%.

IN THE SOUTHWEST AND OTHER CLIMATOLOGICALLY DRY REGIONS - THERE WILL
BE A GREATER THAN 33.3% CHANCE OF NO PRECIPITATION AND OCCASIONALLY
EVEN A NORMAL (I.E. MEDIAN) VALUE OF ZERO - ESPECIALLY DURING THE DRY
SEASONS.  IN SUCH CASES A FORECAST OF NEAR NORMAL IS EFFECTIVELY A
FORECAST OF LITTLE OR NO PRECIPITATION.

THE CLIMATE PREDICTION CENTER USES 1981-2010 BASE PERIOD MEANS FOR
TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN
THE CLIMATE OUTLOOKS.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON
OCTOBER 19

ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
20071031 - 19891012 - 20050927 - 19781028 - 19640928


ANALOGS TO THE 7 DAY MEAN OBSERVED PATTERN CENTERED 4 DAYS AGO (D-4)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 7 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
20071030 - 20050927 - 19581005 - 19781029 - 19891012


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 23 - 27 2017

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    B
SRN CALIF   A    N     IDAHO       A    B     NEVADA      A    B
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B
UTAH        A    B     ARIZONA     A    B     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    A    B     S DAKOTA    A    B
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    N    B
N TEXAS     B    B     S TEXAS     B    B     W TEXAS     A    B
MINNESOTA   N    B     IOWA        N    B     MISSOURI    B    B
ARKANSAS    B    N     LOUISIANA   B    N     WISCONSIN   N    B
ILLINOIS    B    N     MISSISSIPPI B    N     MICHIGAN    N    A
INDIANA     N    A     OHIO        N    A     KENTUCKY    B    A
TENNESSEE   B    A     ALABAMA     B    A     NEW YORK    A    A
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A
MASS        A    A     CONN        A    A     RHODE IS    A    A
PENN        N    A     NEW JERSEY  A    A     W VIRGINIA  N    A
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    N    A
N CAROLINA  N    A     S CAROLINA  N    A     GEORGIA     B    A
FL PNHDL    B    A     FL PENIN    B    A     AK N SLOPE  N    N
AK ALEUTIAN B    A     AK WESTERN  B    N     AK INT BSN  N    N
AK S INT    N    A     AK SO COAST N    A     AK PNHDL    N    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 25 - 31 2017

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    N     OREGON      A    B     NRN CALIF   A    B
SRN CALIF   A    B     IDAHO       A    B     NEVADA      A    B
W MONTANA   A    N     E MONTANA   A    B     WYOMING     A    B
UTAH        A    B     ARIZONA     A    B     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    A    B     S DAKOTA    A    B
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    B    B
N TEXAS     B    B     S TEXAS     B    B     W TEXAS     A    B
MINNESOTA   N    B     IOWA        B    B     MISSOURI    B    B
ARKANSAS    B    B     LOUISIANA   B    B     WISCONSIN   N    B
ILLINOIS    B    B     MISSISSIPPI B    B     MICHIGAN    N    N
INDIANA     B    B     OHIO        B    N     KENTUCKY    B    B
TENNESSEE   B    B     ALABAMA     B    B     NEW YORK    A    A
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A
MASS        A    A     CONN        A    A     RHODE IS    A    A
PENN        N    N     NEW JERSEY  A    A     W VIRGINIA  B    N
MARYLAND    N    N     DELAWARE    A    N     VIRGINIA    B    N
N CAROLINA  B    N     S CAROLINA  B    N     GEORGIA     B    B
FL PNHDL    B    B     FL PENIN    B    N     AK N SLOPE  N    A
AK ALEUTIAN N    A     AK WESTERN  N    N     AK INT BSN  A    A
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    A

                           LEGEND
TEMPS WITH RESPECT TO NORMAL     PCPN WITH RESPECT TO MEDIAN
A - ABOVE   N  - NEAR NORMAL     A - ABOVE   N - NEAR MEDIAN
B - BELOW                        B - BELOW

THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.

FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS
PMDMRD.

$$




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